Electrode very low frequency radio receiving antenna for submarines



June 24, 1958 J. D. BROWDER 2,840,700

ELECTRODE VERY LOW FREQUENCY RADIO RECEIVING ANTENNA FOR SUBMARINESFiled June 30, 1954 2 Sheets-Sheet 1 INVENTOR.

JEWEL D. BROWDER A TTORNEYS June 24, 1958 J. D. BROWDER 2,340,700

ELECTRODE VERY Low FREQUENCY RADIO RECEIVING ANTENNA FOR SUBMARINESFiled June 30, 1954 2 Sheets-sheaf 2 if; Fig. 4

COUPLING 7 UNIT RECEIVER EXTERIOR INTER/0R RECEIVER 2124 I s/o/vAL Invpur 3 c/Rcu/r c INVENTOR. COUPLING JEWEL 0. BROWDER UNIT BY ATTORNEYSUnited States Patent ELECTRODE VERY LOW FREQUENCY RADIU RECEIVINGANTENNA FOR SUBMARINES Jewel D. Browder, San Diego, Calif.

Application June 30, 1954, Serial No. 440,559

Claims. ((11. 250--) (Granted under Title 35, U. S. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

The present invention relates to an electrode V. L. F. (very lowfrequency) radio receiving antenna for submarines and more particularlyto an electrode radio receiving antenna for submarines which abstractssignal energy from the electric field of passing radio waves instead ofthe conventional method of abstracting energy from the magnetic fieldand in which at least one of the two requisite electrodes is permanentlysecured to the top surface of the fairwater of the submarine, the otherelectrode being a second permanently secured one or, in the alternative,may be the existing retractable whip antenna.

Heretofore fixed or rotatable loop receiving antennae have beenemployed. While the electrode radio receiving antenna of the presentinvention and the conventional loop receiving antenna perform equally aswell with respect to signal-to-noise ratio, figure-of-eight directivitypattern and signal strength versus submarine depth, the electrode systemof the present invention excels with respect to weight, simplicity,adaptability, dependability, installation costs, and maintenance costs.

The present invention employs in a submarine radio receiving system twoelectrodes, one of which may be the existing whip antenna, electricallyconnected in series to the input circuit of a radio receiver. The radiosignals are received in the form of minute currents driven through thereceivers input circuit by the potential difference existing between theelectrodes. Reception when the submarine is surfaced is a result of thedistributed capacitance between the lower electrode and the surface ofthe fairwater whereas, when submerged the electrode receiving systemoperates by virtue of the horizontal electric field which produces auseful radio-signal potential difference between the two electrodesspaced a few feet apart.

The upper electrode may consist of the existing submarine retractablewhip antenna or a long narrow metal strap type electrode mounted in aninsulating support secured to the top surface of the fairwater. Theformer has the advantage that it may be extended upward toward the seasurface and thereby effect a higher received signal level, permittingreception at deeper submergence depths. Since the whip antenna cannotnormally perform its usual functions when the base of the whip does notclear the surface of the sea, the whip antenna makes an effective upperelectrode for the electrode receiving system duringfs ubmergence when itotherwise is not in use. On the other hand, the latter type of upperelectrode enables theelectrode receiving system to be independentofth'ewhip, and thus free the whip for preforming its normal functionsatall times while the submarine is submerged at periscope' depths. Inthe second arrangement the whip antenna can additionally be used whenadditionalsignal strength is necessary.

an improved system of receiving V. L. F. radio signals on board asubmarine which is simple, light-weight, reliable, and economical.

Another object of the present invention is the provision of a submarineradio receiving antenna comparable to conventional loop antennae insignal-to-noise ratio, figureof-eight directivity pattern and signalstrength versus submarine depth characteristics.

Another object is the provision of a receiving antenna system whichexcels known systems with respect to weight, simplicity, adaptability,dependability, installation and maintenance costs.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

Fig. l is a pictorial view showing the relationship of the electrodes onthe fairwater and deck of the submarine;

Fig. 2 is a pictorial view of one of the electrodes mounted to thefairwater top;

Fig. 3 is a block diagram of the coupling unit and its interconnections;and

Fig. 4 is a schematic diagram showing the noise reduction circuit.

It has been shown that the total energy of a V. L. F. radio wave isequally divided between the electric and magnetic fields of the wave,both when the wave is propagating in space above the sea surface andwithin the sea water itself. In spaceabove the sea surface where thedirection of wave propagation is parallel with the earths surface, theelectric field is polarized almost vertically and the magnetic fieldhorizontally at right angles with the direction of wave propagation.However, in sea water the direction of wave propagation is downwardtoward the earths center and both the electric and mag netic fields arepolarized almost horizontally or parallel with the earths surface butdisplaced by 90 degrees in the horizontal plane, with the electric fieldparallel with the direction of wave propagation above the sea surface.Thus, in sea water the electrode receiving system of the presentinvention operates by virtue of the horizontal electric field whichproduces a useful radio signal potential difference between twoelectrodes separated by a few feet. When these electrodes areelectrically joined together with insulated conductors which connect-theinput circuit of a radio receiver in series with the electrodes, radiosignals are received in the form of minute currents driven through thereceivers input circuit by the potential difference existing between theelectrodes.

The highest level of signal energy is just below the surface of the seaand as the radio wave propagates downwardly, it is attenuated in db permeter at the rate of 0.034%, where f is depth in-feet, which amounts toapproximately 1.25 db per foot for a 20 kc. wave. This means that apotential difference exists between two elec trodes separated by a smalldistance in a vertical plane. A potential difference also exists betweensubmerged electrodes located in a horizontal plane and separated by afew feet by virtue of the phase difference of the sinusoidally varyingfield between the two electrodes. Thus signals can be received from twoelectrodes located either in a vertical plane, horizontal plane, or anyintermediate plane, the latter planes obviously having horizontal andvertical components of electrode displacements.

Through experimentation it was found that as one of the two electrodesis lengthened and oriented more or less parallel with the electric fieldof the radio waves to be received, the energy level of received signalsis greatly increased. Referring now to the drawings, wherein likereference characters designate like or corresponding parts throughoutthe several views, there is shown in Fig. l the preferred positions ofarrangement of the upper electrodes 11 and 11A mounted on the fairwatersurface and lower electrodes 12 and 12A mounted on the main deck 10.Because of the directivity pattern being a figure eight configuration,two sets of upper and lower electrodes, 11, 11A, 12, and 12A, are placedat right angles to each other with a pair of single pole double throwswitching mechanism 34 conveniently placed such that the operator mayeasily switch from one set to the other in order to effect anomnidirectional reception pattern. Electrodes 11 and 12 will behereinafter described in connection with the electrode receiving system,although it is obvious that electrodes 11A and 12A are similarlyconstructed and utilized. Due consideration must be given to the signallevel, noise effects, and directivity pattern, influenced by suchsalient factors as impedance matching of the electrode and receiverinput circuits, the most effective type of wiring of conductors throughthe pressure hull, and analyzing the various kinds of noise disturbancesand effecting their maximum reduction. Corresponding ends of upperelectrode 11 and lower electrode 12 are joined to the signal inputcircuit of the receiver, as illustrated by ends 13 which are the forwardends as shown in Fig. 1. These connections however may be reversed oreven staggered without seriously affecting the performance of theelectrode antenna. All four electrodes are more or less identical inconstruction.

As best shown in Fig. 2, the upper electrode 11, preferably of stainlesssteel or other corrosion resistant material, is flush mounted on alinenized Micarta base 14, insulating it from the fairwater top surface.The upper electrode 11 and its base 14 weigh approximately 15 pounds ascompared to the approximate weight of one ton for a conventional loopreceiving antenna including its retractable mechanism. End 13 of upperelectrode 11 is joined to connecting coaxial cable 16 which protrudesthrough a brass bushing 17 mounted through a hole in the fairwater topsurface 10. The outer covering of coaxial cable 16 comprises a flexiblecopper shield 18 insulated from conductor 15 by insulation 30 andcovered by external insulating jacket 19. Bushing 17 comprises twothreaded metallic members, such as brass, secured by use ofshock-absorbing washers 20. At bushing 17 the shield 18 is grounded tothe metal of fairwater 10. Electrical connection is made between thecopper conductor 15 of coaxial cable 16 and the end 13 of electrode 11bent at right angles to its axis. This connection is given a heavycoating of Glyptal or other waterproof compound to prevent corrosion.

Coupling unit 21, shown in block diagram in Fig. 3, is for the purposeof providing an impedance match with electrodes 11 and 12, signal inputcircuit 36, and the antenna input circuit of conventional types of V. L.P. receivers 22. To do this without losing signal strength, a vacuumtube amplifier may be used having a tuned input over the V. L. F. band.Power for the amplifier may be gotten from the power supply of thereceiver 22 which is equipped with filters in the A. C. power lineswhich reduce additional noise from the power system.

Noise is a major problem in the practical operation of both theelectrode receiving system of this invention and the conventional loopantenna receiving system. Noise disturbances fall into three majorclassifications, those that get into the receiver via the A. C. powersystem. those due to potential differences between the interior andexterior surfaces of the submarine hull, and those due to atmosphericsand the submarines underwater electrical potential. The first type hasbeen generally eliminated or at least greatly reduced in amplitude byuse of adequate filters in the power inputleads of the receiver powersupply.

Noise disturbances of the second type originate in other electricalequipments aboard the sub and are not only impressed on the power lineslike those of the first type but also they produce potential differencesbetween the interior and exterior surfaces of the hull as indicateddiagrammatically by the generator in Fig. 4. Voltage and current wavesthus propagate along the interior and exterior surfaces of the pressurehull. T hesc are of little consequence in the conventional loop antennareceiving system as the signal input of this system is balanced toground (hull). However, they present a problem which must be met inpracticing the present invention.

In the electrode receiving system of the present invention the signalinput circuit 36 must also be balanced to ground, which is effected bythe potentiometer 24, Fig. 4, connected in shunt with the signal inputtransformer 26. The potentiometer 24 with its slide 27 comprises aportion of a balanced bridge, the remaining portions being establishedupon submergence of the submarine. In Fig. 4 is shown the equivalentcircuit of the balanced bridge, Where 23 and 29 represent the impedancesbetween the upper electrode 11 and hull 31 and between the lowerelectrode 12 and hull 31, respectively. These are the impedances of thesea water between the electrodes and hull, having magnitudes in theorder of 1 to 3 ohms, while those of the other arms of the bridge, 32and 33 of potentiometer 24, are in the order of 1,000 ohms each. Thebalance effected by proper placement of the slide is not critical overthe V. L. F. band and the bridge may be out of exact balance either waybefore the resistive components of the noise disturbances of the secondtype are audible. The capacitive components of the noise currents innoise of the second type, while not so great as the resistivecomponents, are also damped out. Without the cable shields 18 acapacitance exists between the sea water and the conductor 15. Change inspeed and other conditions constantly change the amount of capacitance,causing noise disturbances in the receiver. By the use of shields 18,this capacitance can be controlled. As shown in Fig. 4 these shields aregrounded to the exterior surface of the hull 31 and are connectedtogether at their inner ends by a variable potentiometer 23 whose slidewire is grounded to the interior of the hull. Since the coaxial cablesare of unequal lengths, their capacitances between shield and innerconductor must be equalized or balanced. This is done by connectingvariable condensers 25 between the conductors 15 and shields 18 of eachcable 16 coupling unit 21, shown in block diagram, couples the output oftransformer 26 with the input of receiver 22.

The third type of noise disturbances, i. e., those due to atmosphericsand the submarines underwater electrical potential (hereinafter referredto as UEP), are the most diificult to eliminate since they enter thereceiver in the same manner as signals enter, i. e., by virtue of thepotential difference between the electrodes or induced po tentials onthe conventional loop receiving antenna. This type of noise disturbanceis divided into two subgroups, namely, atmospheric or static, and waternoise or noise due to variations caused by water turbulence which, inturn, is governed by the motion of the submarine. These noises usuallybecome barely audible in both the electrode and loop antenna systems atrelatively low speeds of a submerged submarine. While the elimination ofthis type of noise is not found in the apparatus of the presentinvention, it is desired to point out that the electrode receivingsystem of the present invention is able to cope with the situation withability equal to that of conventional loop systems.

While the electrode system has been described as utilizing two upperelectrodes and two lower electrodes, each at right angles to the other,an obvious modification would be to employ rotatable antennas. A furthermodification would be the utilization of the submarines whip antenna asthe upper electrode or used together with the upper electrode forgreater signal reoepn'on.

Both lower electrodes 12 and 12A are flush mounted with deck surface soas to offer little or no obstruction to normal traffic on the deck. Tofurther clear the deck electrode 12A which functions electrically withupper electrode 11A may be installed on the side apron of the decksuperstructure, below the elevation of deck surface 10 but parallel toupper electrode 11A. To completely clear the deck another alternative isto combine both lower electrodes into a single electrode of smallerphysical dimensions, mounted on the side apron below the deck surfaceand with the upper electrodes only so connected with one single poledouble throw switch 34 that the lower combined electrode serves as acommon elec trode with each of the upper electrodes 11 ad 11A. Thisalternative should yield a slightly reduced received signal strength butstill retain the omnidirectional pattern.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. Apparatus for receiving very-low-frequency signals from the electricfield of passing radio waves comprising a first upper electrode, a firstlower electrode, a second upper electrode substantially at right anglesto said first electrode, and a second lower electrode substantially atright angles to said first lower electrode, an input circuit connectingone upper and one lower electrode to a receiver, and switching means foralternately connecting the first upper and lower electrodes and secondupper and lower electrodes to said input circuit.

2. Apparatus for receiving very-low-frequency signals from the electricfield of passing radio waves comprising a first long narrow upperelectrode; a first lower electrode, a second long narrow upper electrodesubstantially at right angles to said first electrode, both said upperelectrodes secured to the fair-water surface of a submarine, and asecond lower electrode substantiallyat right angles to said first lowerelectrode, both said lower electrodes secured to the surface of the maindeck of said submarine, an input circuit connecting one upper and onelower electrode to a receiver, and switching means for alternatelyconnecting the first upper and lower electrodes and second upper andlower electrodes to said input circuit.

3. Apparatus for receiving very-low-frequency signals from the electricfield of passing radio waves comprising a first upper electrode, a firstlower electrode, a second upper electrode substantially at right anglesto said first electrode, and a second lower electrode substantially atright angles to said first lower electrode, said first upper electrodeplaced substantially parallel to and spaced above said first lowerelectrode, said second upper electrode placed substantially parallel toand spaced above said second lower electrode, an input circuitconnecting one upper and one lower electrode to a receiver, andswitching means for alternately connecting the first upper and lowerelectrodes and second upper and lower electrodes to said input circuit.

4. Apparatus for receiving very-loW-frequency signals from the electricfield of passing radio waves comprising a first upper electrode, a firstlower electrode, a second upper electrode substantially at right anglesto said first electrode, and a second lower electrode substantially atright angles to said first lower electrode, said electrodes beingmounted on the outer surface of the hull of a vessel, a receiver, aninput circuit connected to said receiver, and switching means foralternately connecting the first upper and lower electrodes and secondupper and lower electrodes to said circuit, said circuit comprising aplurality of adjustable impedance means having connection to the innersurface of the hull of said vessel for reducing noise voltage betweensaid outer and inner surfaces.

5. Apparatus as in claim 4 wherein said impedance 6 means comprisesfirst and second impedance branches connected in parallel.

6. Apparatus as in claim 5 wherein said first branch comprisespotentiometer means having a slide connected to said inner surface.

7. Apparatus as in claim 5 wherein said second branch comprisesadjustable condenser means,

8. Apparatus as in claim 7 wherein said second branchfurther comprisespotentiometer means connected in series with said condenser means, saidpotentiometer means having a slide connected to said inner surface.

9. Apparatus as in claim 5 wherein said second branch comprisesconductors connected to said electrodes, said conductors havinginsulation and shields thereover, said shields being connected to saidouter surface, a plurality of adjustable condenser means connected toeach of said shields and one of said conductors, and potentiometer meansconnected to said shields and having a slide connected to said innersurface.

10. Apparatus for receiving very-low-frequency signals from the electricfield of passing radio waves comprising a first upper electrode, a firstlower electrode, a second upper electrode substantially at right anglesto said first electrode, and a second lower electrode substantially atright angles to said first lower electrode, said electrodes beingmounted on the outer surface of the hull of a vessel, a receiver, aninput circuit connected to said receiver, and switching means foralternately connecting the first upper and lower electrodes and secondupper and lower electrodes to said circuit, said circuit comprisingfirst and second impedance branches connected in parallel, said brancheseach having a, potentiometer with a movable slide connected to the innersurface of the hull of said vessel for reducing noise voltage betweensaid outer and inner surfaces.

11. Apparatus for receiving very-low-frequency signals from the electricfield of passing radio waves comprising a first upper electrode, a firstlower electrode, a second upper electrode substantially at right anglesto said first electrode, and a second lower electrode substantially atright angles to said first lower electrode, said electrodes beingmounted on the outer surface of the hull of a vessel, conductorsconnected to a receiver, said conductors having insulation and shieldsthereover, said shields being connected to said outer surface, switchingmeans for alternately connecting the first upper and lower electrodesand second upper and lower electrodes to said conductors,

and first and second adjustable impedance means connected to saidconductors and the inner surface of said hull for reducing noise voltagebetween said outer and inner surfaces.

12. Apparatus as in claim 11 wherein said first impedance meanscomprises potentiometer means having a slide connected to said innersurface.

13. Apparatus as in claim 11 wherein said second impedance meanscomprises potentiometer means having a.

slide connected to said inner surface.

14. Apparatus for receiving very-low-frequency signals:

from the electric field of passing radio waves comprising upper andlower electrodes mounted on the outer surface of the hull of a vessel,conductors connected to said elec-- trodes, said conductors havinginsulation and shields thereover, said shields being connected to saidouter surface, a receiver connected to said conductors, firstpotentiometer means connected to said conductors and having a slideconnected to the inner surface of the hull of said vessel, adjustablecondenser means connected between each of said shields and one of saidconductors,.

and second potentiometer means connected to said shields and having aslide connected to said inner surface, whereby adjustment of saidcondenser means and said slides reduces noise voltage between said outerand inner surfaces.

15. Apparatus for receiving very-low-frequency signals from the electricfield of passing radio waves comprising upper and lower electrodesmounted on the outer sur' face of the hull of a vessel, a receiver, andinput circuit means comprising an impedance branch connected in parallelto said receiver, said branch having conductors with insulation andshields thereover connected to said electrodes, said shields beingconnected to said outer surface, adjustable condenser means connected toeach of said shields and one of said conductors, and potentiometer meansconnected to said shields, said potentiometer means having a slideconnected to the inner surface of the hull of said vessel, wherebyadjustment of said capacitor means and said slide reduces noise voltagebetween said outer and inner surfaces.

References Cited in the file of this patent UNITED STATES PATENTS RogersMay 13, 1919 Rogers Aug. 16, 1921 Jones Oct. 16, 1923 Willoughby et al.Apr. 9, 1929 Ilberg May 21, 1935 Whisk Dec. 6, 1938 Whisk Apr. 21, 1942Bruce Mar. 9, 1943 Hampshire et al Nov. 24, 1953 Mural Dec. 29, 1953

